1. Field of the Invention
The present invention relates to a new and improved apparatus for interconnecting two groups of driers of a papermaking machine.
Generally speaking, the apparatus for interconnecting two groups of driers of a papermaking machine, wherein the groups of driers are suitable for drying a paper web, according to the present development is of the type wherein the paper web is guided together with at least one endless drying wire over heated drying devices, especially drying cylinders or rollers, in such a manner that the paper web is located between the drying wire and an associated drying device. At least two groups of driers successively follow one another in a predetermined direction of travel of the paper web through such groups of driers. At a transition location between the two groups of driers the paper web is guided from the one preceding group of driers into the next following or successive group of driers in such a manner that the opposite side of the paper web, which is situated opposite to the side of the paper web contacted or dried by the preceding group of driers and which faced the drying devices thereof, is now located in the direction of the drying devices of such next following group of driers. In this next following group of driers there is used a different endless drying wire than the endless drying wire used in the preceding group of driers. As viewed in the predetermined direction of travel of the paper web, downstream of the last drying device of the preceding group of driers there is provided at least one deflection roller for deflection of the endless drying wire together with the paper web as well as a following deflection roller for the drying wire which at that location is without or no longer carries the paper web. In the following group of driers at a location upstream of the first drying device of this following group of driers the endless drying wire of such following group of driers is guided over a deflection roller to the endless drying wire of the preceding group of driers and forms together with the paper web and the endless drying wire of the preceding group of driers a contact region. Following separation of the endless drying wire of the preceding group of driers from the paper web the endless drying wire of the following group of driers is guided in conjunction with the paper web over a deflection device belonging to the following group of driers and from which the paper web can then be guided to the first drying device of the following group of driers.
2. Discussion of the Background and Material Information
In the German Petty Patent No. 90 01 209.7, granted Apr. 5, 1990, there is disclosed an apparatus for connecting or interconnecting two groups of driers of a papermaking machine and, when necessary, separating or disconnecting such two groups of driers. The separation of two successive groups of driers, as is known in the papermaking art, can be desired when one group of driers should be stopped for operational reasons, but at the same time the other group of driers should remain operational. With this known solution there can be adjusted, for instance, an upper situated drying wire-guide roll into a number of positions, with the result that there can be varied both the wrap angle of a lower situated suction deflection roller, from where the paper web is transferred from the one group of driers to the other group of driers, and there can be effectuated a separation or disconnection of both groups of driers from one another.
However, prior art web transfer apparatuses of this type are afflicted with the drawback that the transfer of the paper web from one to the other felt must be accomplished along a relatively short path. This can result in uncertainty in the web transfer operation, or there can result, during web transfer, with a corresponding large wrap angle, impairment in the quality of the sensitive paper web.